MAIG and some progressive and liberal groups have pledged to hold accountable the four Democratic senators who voted against the background check measure. MAIG’s spot hitting Pryor is its first, however, against a Democrat. It has also gone after Sens. Jeff Flake (R-Ariz.) and Kelly Ayotte (N.H.).

The ad against Pryor — a $350,000 buy — features Angela Bradford-Barnes, who stares into the camera and says she is “disappointed” in Pryor’s vote. Bradford-Barnes worked with former State Democratic Party Chair Bill Gwatney, who was brutally murdered in 2008 at the state Democratic Party headquarters.

Pryor was also a friend of Gwatney — he eulogized Gwatney on the Senate floor shortly after his death in 2008. That’s perhaps why he so forcefully tried to dismiss the ad from Bloomberg’s group, releasing a scathing statement Friday afternoon.

“New York City Mayor Mike Bloomberg didn’t know Bill Gwatney. I knew Bill Gwatney. He was my friend and he was killed by someone with severe mental health issues,” Pryor said in the statement. “The Mayor’s bill would have done nothing to prevent his death because it fails to adequately address the real issue and common thread in all of these shootings—mental health.”

” … Mayor Bloomberg’s attack ad politicizes the death of my friend by misleading people into thinking that his bill would have prevented Bill Gwatney’s tragic death. The fact is it wouldn’t have, which makes Mayor Bloomberg’s ad even more disgusting.”

A spokeswoman for Bloomberg’s group pushed back at Pryor’s statement, noting that Bradford-Barnes didn’t attempt to say it would have changed anything about Gwatney’s death.

“This bill may not be perfect, and it cannot undue my tragic loss, but if it stops even one person from causing this pain to another family, it’s worth it,” she said in a statement. “I hope that if Senator Pryor is given another chance to lead on this issue he thinks first about Arkansas voters like me.”

Here’s the ad, which is running on Arkansas broadcast and cable for two weeks: